Early contact lenses have been known with photochromic liquid held in a reservoir disposed between two materials forming a contact lens as part of a protective system against intense flashes such as a nuclear detonation.
More recently, efforts have been directed towards photochromic contact lenses that can be worn daily and that quickly transition between colored and uncolored states utilizing photochromic dyes capable of absorbing light in specific wavelength ranges. In some examples, a dye is dispensed in a lens capable of exhibiting photochromism in the polymeric material comprising the contact lens so as to preferably have a single layer capable of absorbing light. However the contact lenses that exhibit photochromism throughout the entire lens area, “edge-to-edge”, are not desired due to cosmetic reasons.
Therefore, efforts have been made to create a contact lens that changes color only in the central pupil region, “pupil-only” contact lens.
US2003/0142267 discloses contact lenses having a photochromic material in the center or pupil region of the lens only. The lens is made by dispensing monomer mixes having different viscosities into the lens mold. The contact lenses are hard contact lenses which have no water content. The process disclosed in US2003/0142267 does not produce soft, hydrogel contact lenses which have desirable properties such as good optics and comfort.
There is a need for an improved pupil only photochromic contact lens, including a method of manufacturing such lenses, that exhibits reduced deformation and optical distortion and increased comfort, wear ability, and cosmetic appearance.